ProductAttributeValue issue/nopcommerce oversite

So, I've had my nopcommerce site running about 3 months now which sells car parts.  To make my life easier and to keep the number of products per upload down, I have one spreadsheet per car.  This is all well and good and allows me to amend stock, pricing etc, however, when I come to add another Product Attribute, the spreadsheet has to have a unique ProductAttributeValue number assigned to it which is fine if you're starting a new spreadsheet, but if I want to add to an existing one, it can't be done as the number don't line up.

For example, bush type on one car has the ProductAttributeValues of 8 and 9, but 10 is already used by another item.  I use the next available which would be 487 in this case, but uploading it from fresh means it won't work as it's not entered all the numbers that come before it in the MSSQL data base and only writes in order.  It then just ends up staggering all the attributes wrong out by 1.

How do I get around this without adding attributes in the back office which is a complete pain?

Any idea how to get around this problem.  Not being able to retrospectively add product attributes makes my website completely useless as it isn't future proof.

Or is this something that isn't possible in Nopcommerce and I should look towards one of the other eCommerce solutions such as presta or magento?